The present invention relates to a blackboard, and more particularly to a writing board which comprises an automatic erase device for erasing the writing on the board automatically.
The most common method of erasing a blackboard in a classroom or a meeting room is to use a hand-held eraser and to manually erase the blackboard as required. A progressive disadvantage of the conventional blackboard is that the lecturer has to stop his writing from time to time for erasing manually. The chalk dust flies in the air during the erasing. Therefore, the air will be polluted that does harm to human health.
As the size of the blackboard and the expanse of coverage increase, the people who sit at the left or right corner will find difficult to observe the writing on the far side of the blackboard due to reflection. The traditional blackboard is fixed on the wall. The writing at the bottom of the blackboard will remain at the lower position that is more difficult to be viewed by those people who sit at the back seats than the writing at a upper position of the fixed blackboard. Moreover, the lecturer has to stand in front of the blackboard while writing that will obstruct the portion of the blackboard being writing upon from the student's view.
U.S. Pat. No. 4, 462,134, and 4,742,594 are patents about the blackboard handhold eraser. U.S. Pat. No. 3,731,335 and 3,858,265 are patents concern about automatic chalkboard eraser mounted on the conventional chalkboard. The above prior arts disclose the art of eraser with unsolved drawbacks as described above.